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m68k: Use kernel's generic muldi3 libgcc function

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Use the kernels own generic lib/muldi3.c implementation of muldi3 for
68K machines. Some 68K CPUs support 64bit multiplies so move the arch
specific umul_ppmm() macro into a header file that is included by
lib/muldi3.c. That way it can take advantage of the single instruction
when available.

There does not appear to be any existing mechanism for the generic
lib/muldi3.c code to pick up an external arch definition of umul_ppmm().
Create an arch specific libgcc.h that can optionally be included by
the system include/linux/libgcc.h to allow for this.

Somewhat oddly there is also a similar definition of umul_ppmm() in
the non-architecture code in lib/crypto/mpi/longlong.h for a wide range
or machines. Its presence ends up complicating the include setup and
means not being able to use something like compiler.h instead. Actually
there is a few other defines of umul_ppmm() macros spread around in
various architectures, but not directly usable for the m68k case.

Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
Link: https://lore.kernel.org/20231113133209.1367286-1-gerg@linux-m68k.org
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
This commit is contained in:
Greg Ungerer 2023-11-13 23:32:09 +10:00 • committed by Geert Uytterhoeven
parent 40384c840e
commit e419ddeabe
6 changed files with 35 additions and 98 deletions
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8
arch/Kconfig
View file

@ -1526,6 +1526,14 @@ config HAVE_ARCH_COMPILER_H
linux/compiler-*.h in order to override macro definitions that those
headers generally provide.
config HAVE_ARCH_LIBGCC_H
bool
help
An architecture can select this if it provides an
asm/libgcc.h header that should be included after
linux/libgcc.h in order to override macro definitions that
header generally provides.
config HAVE_ARCH_PREL32_RELOCATIONS
bool
help

2
arch/m68k/Kconfig
View file

@ -23,7 +23,9 @@ config M68K
select GENERIC_LIB_ASHLDI3
select GENERIC_LIB_ASHRDI3
select GENERIC_LIB_LSHRDI3
select GENERIC_LIB_MULDI3
select HAS_IOPORT if PCI || ISA || ATARI_ROM_ISA
select HAVE_ARCH_LIBGCC_H
select HAVE_ARCH_SECCOMP
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ASM_MODVERSIONS

20
arch/m68k/include/asm/libgcc.h Normal file
View file

@ -0,0 +1,20 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_M68K_LIBGCC_H
#define __ASM_M68K_LIBGCC_H
#ifndef CONFIG_CPU_HAS_NO_MULDIV64
/*
* For those 68K CPUs that support 64bit multiply define umul_ppm()
* for the common muldi3 libgcc helper function (in lib/muldi3.c).
* CPUs that don't have it (like the original 68000 and ColdFire)
* will fallback to using the C-coded version of umul_ppmm().
*/
#define umul_ppmm(w1, w0, u, v) \
__asm__ ("mulu%.l %3,%1:%0" \
: "=d" ((unsigned long)(w0)), \
"=d" ((unsigned long)(w1)) \
: "%0" ((unsigned long)(u)), \
"dmi" ((unsigned long)(v)))
#endif /* !CONFIG_CPU_HAS_NO_MULDIV64 */
#endif /* __ASM_M68K_LIBGCC_H */

2
arch/m68k/lib/Makefile
View file

@ -4,7 +4,7 @@
# Makefile for m68k-specific library files..
#
lib-y := muldi3.o memcpy.o memset.o memmove.o
lib-y := memcpy.o memset.o memmove.o
lib-$(CONFIG_MMU) += uaccess.o
lib-$(CONFIG_CPU_HAS_NO_MULDIV64) += mulsi3.o divsi3.o udivsi3.o

97
arch/m68k/lib/muldi3.c
View file

@ -1,97 +0,0 @@
/* muldi3.c extracted from gcc-2.7.2.3/libgcc2.c and
gcc-2.7.2.3/longlong.h which is: */
/* Copyright (C) 1989, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
This file is part of GNU CC.
GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details. */
#include <linux/compiler.h>
#include <linux/export.h>
#include <linux/libgcc.h>
#ifdef CONFIG_CPU_HAS_NO_MULDIV64
#define SI_TYPE_SIZE 32
#define __BITS4 (SI_TYPE_SIZE / 4)
#define __ll_B (1L << (SI_TYPE_SIZE / 2))
#define __ll_lowpart(t) ((USItype) (t) % __ll_B)
#define __ll_highpart(t) ((USItype) (t) / __ll_B)
#define umul_ppmm(w1, w0, u, v) \
do { \
USItype __x0, __x1, __x2, __x3; \
USItype __ul, __vl, __uh, __vh; \
\
__ul = __ll_lowpart (u); \
__uh = __ll_highpart (u); \
__vl = __ll_lowpart (v); \
__vh = __ll_highpart (v); \
\
__x0 = (USItype) __ul * __vl; \
__x1 = (USItype) __ul * __vh; \
__x2 = (USItype) __uh * __vl; \
__x3 = (USItype) __uh * __vh; \
\
__x1 += __ll_highpart (__x0);/* this can't give carry */ \
__x1 += __x2; /* but this indeed can */ \
if (__x1 < __x2) /* did we get it? */ \
__x3 += __ll_B; /* yes, add it in the proper pos. */ \
\
(w1) = __x3 + __ll_highpart (__x1); \
(w0) = __ll_lowpart (__x1) * __ll_B + __ll_lowpart (__x0); \
} while (0)
#else
#define umul_ppmm(w1, w0, u, v) \
__asm__ ("mulu%.l %3,%1:%0" \
: "=d" ((USItype)(w0)), \
"=d" ((USItype)(w1)) \
: "%0" ((USItype)(u)), \
"dmi" ((USItype)(v)))
#endif
#define __umulsidi3(u, v) \
({DIunion __w; \
umul_ppmm (__w.s.high, __w.s.low, u, v); \
__w.ll; })
typedef int SItype __mode(SI);
typedef unsigned int USItype __mode(SI);
typedef int DItype __mode(DI);
typedef int word_type __mode(__word__);
struct DIstruct {SItype high, low;};
typedef union
{
struct DIstruct s;
DItype ll;
} DIunion;
DItype
__muldi3 (DItype u, DItype v)
{
DIunion w;
DIunion uu, vv;
uu.ll = u;
vv.ll = v;
w.ll = __umulsidi3 (uu.s.low, vv.s.low);
w.s.high += ((USItype) uu.s.low * (USItype) vv.s.high
+ (USItype) uu.s.high * (USItype) vv.s.low);
return w.ll;
}
EXPORT_SYMBOL(__muldi3);

4
include/linux/libgcc.h
View file

@ -34,4 +34,8 @@ long long notrace __lshrdi3(long long u, word_type b);
long long notrace __muldi3(long long u, long long v);
word_type notrace __ucmpdi2(unsigned long long a, unsigned long long b);
#ifdef CONFIG_HAVE_ARCH_LIBGCC_H
#include <asm/libgcc.h>
#endif
#endif /* __ASM_LIBGCC_H */